Well, it is a medium severe bug, because it concerns only the lines with coupling constants.
K1 L1 L2 1
will not be entered into the netlist, all others (dot commands or .control … .endc sections) will be copied from the text box into the netlist.
As a workaround you have to use a .lib file with an inductor subcircuit.
A bug report is filed (https://bugs.launchpad.net/kicad/+bug/1815281).
You may enter a ‘me too’ to this report.